The overall objective of this proposal is to develop a species of small marsupial, Monodelphis domestica, as an economical and convenient laboratory animal for biomedical research. The availability of a laboratory marsupial would enable many novel research projects concerning developmental processes because marsupials are born at a very early stage of development and exist thereafter as extra-uterine "fetuses," which can be easily manipulated for experimental purposes. The primary aims are to develop a simple and economical diet, to simplify current husbandry procedures, to characterize genetic diversity in the colony and to develop a rational strategy of genetic management. In the process of accomplishing the above primary aims we expect also to establish a safe method for anesthetizing animals, to establish baseline parameters of hematology and serum chemistry, and to determine clinical manifestations of disease by pathological and microbiological examination of healthy and diseased specimens. It is anticipated that the pilot studies proposed here will lead to the establishment of M. domestica as a common laboratory animal and to its exploitation in studies of developmental biology, cancer, gene regulation, and other major areas of health-related research.